Three-Component Photochemical Cyclization/Dithiocarbamate Formation of <i>gem</i>-Difluoro Quinolin-2(1<i>H</i>)-ones
Fei Chen, Gangqing Shi, Yang Zheng, Qinghao Dong, Peng Wei, Rentian Wang, Er‐Jun Hao, Xin Wang, Kai Sun
Abstract
Herein, a novel visible-light-induced 6- exo-trig difluoromethylation cyclization and subsequent carbo-thioesterification reaction is described. This protocol allows efficient access to valuable gem -difluoro quinolin-2(1 H )-ones in moderate to excellent yields under mild conditions. Broad amino sources compatibility, including cyclic morpholine, thiazolidine, thiomorpholine, pyrrolidine, 1,4-oxazepane, 2,6-dimethylmorpholine, tert -butyl piperazine-1-carboxylate and noncyclic diethylamine, N -ethylpropan-1-amine, N -benzylethanamine, N -benzyl-trimethylsilanamine, dibenzylamine, and N -(4-methoxybenzyl)ethanamine, demonstrated the practicability of this strategy. A radical–radical crossover route was proposed on the basis of radical inhibition experiments, visible light irradiation on–off test, apparent quantum efficiency (AQE) calculation, and fluorescence quenching studies.